﻿/*******************************************************
*
* 函数名称：Base64encode()
* 功    能：对数据进行Base64加密
* 说	明：函数中将数据使用_utf8_encode()进行编码转换后再加密,保证数据完整
*
**********************************************************/

var _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

function _Base64encode(input) {

	var output = "";
	var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
	var i = 0;

	input = _utf8_encode(input);

	while (i < input.length) {

		chr1 = input.charCodeAt(i++);
		chr2 = input.charCodeAt(i++);
		chr3 = input.charCodeAt(i++);

		enc1 = chr1 >> 2;
		enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
		enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
		enc4 = chr3 & 63;

		if (isNaN(chr2)) {
			enc3 = enc4 = 64;
		} else if (isNaN(chr3)) {
			enc4 = 64;
		}

		output = output + this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) + this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
	}
	return output;
}

/*******************************************************
*
* 函数名称：Base64decode()
* 功    能：对数据进行Base64解密
* 说	明：函数中将数据使用_utf8_decode()将解密后的数据编码,保证数据完整
*
**********************************************************/
function _Base64decode(input) {
	var output = "";
	var chr1, chr2, chr3;
	var enc1, enc2, enc3, enc4;
	var i = 0;

	input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

	while (i < input.length) {

		enc1 = this._keyStr.indexOf(input.charAt(i++));
		enc2 = this._keyStr.indexOf(input.charAt(i++));
		enc3 = this._keyStr.indexOf(input.charAt(i++));
		enc4 = this._keyStr.indexOf(input.charAt(i++));

		chr1 = (enc1 << 2) | (enc2 >> 4);
		chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
		chr3 = ((enc3 & 3) << 6) | enc4;

		output = output + String.fromCharCode(chr1);

		if (enc3 != 64) {
			output = output + String.fromCharCode(chr2);
		}
		if (enc4 != 64) {
			output = output + String.fromCharCode(chr3);
		}

	}

	output = _utf8_decode(output);

	return output;
}

/*******************************************************
*
* 函数名称：_utf8_encode()
* 功    能：将数据进行utf8编码
* 说	明：
*
**********************************************************/
function _utf8_encode(string) {
	string = string.replace(/\r\n/g,"\n");
	var utftext = "";

	for (var n = 0; n < string.length; n++) {

		var c = string.charCodeAt(n);

		if (c < 128) {
			utftext += String.fromCharCode(c);
		}
		else if((c > 127) && (c < 2048)) {
			utftext += String.fromCharCode((c >> 6) | 192);
			utftext += String.fromCharCode((c & 63) | 128);
		}
		else {
			utftext += String.fromCharCode((c >> 12) | 224);
			utftext += String.fromCharCode(((c >> 6) & 63) | 128);
			utftext += String.fromCharCode((c & 63) | 128);
		}
	}
	return utftext;
}

/*******************************************************
*
* 函数名称：_utf8_decode()
* 功    能：将数据进行utf8解码
* 说	明：
*
**********************************************************/
function _utf8_decode(utftext) {
	var string = "";
	var i = 0;
	var c = c1 = c2 = 0;

	while ( i < utftext.length ) {

		c = utftext.charCodeAt(i);

		if (c < 128) {
			string += String.fromCharCode(c);
			i++;
		}
		else if((c > 191) && (c < 224)) {
			c2 = utftext.charCodeAt(i+1);
			string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
			i += 2;
		}
		else {
			c2 = utftext.charCodeAt(i+1);
			c3 = utftext.charCodeAt(i+2);
			string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
			i += 3;
		}
	}
	return string;
}
